It is well known in the art, that during the production of tampons, tampon pledgets have a tendency to re-expand to their original dimensions after a compression step. Heat setting has been utilized to overcome this tendency. Heat setting is the application of heat to a compressed tampon pledget designed to “set” or stabilize the tampon in the compressed state. Currently, tampons are set or stabilized by either conductive heating or microwave heating, both of which have drawbacks.
Commonly, conductive heating methods do not uniformly stabilize the tampon and may result in the alteration of absorbent qualities in the outer layer of the tampon because the dense, compacted material on the outside of the tampon dries more quickly than the inside. Conductive heating methods may also be time intensive because the air inside the tampon must be heated to dry the fibers via conduction from outside the pledget to the inside. As well, high temperatures that may decrease cycle times cannot be utilized in conductive heating methods because these temperatures may be above the melting point of tampon overwraps resulting in a melted product.
While microwave heating can be a faster method of stabilizing tampons than conductive heating, microwave heating does not uniformly stabilize tampons and may create “hot spots” within the tampon and may also melt the overwrap of the tampon. As well, only a small fraction of the outputted energy in microwave heating actually goes into stabilizing the tampon, thus energy costs of this method are relatively high.
The present invention addresses the problems associated with both the conductive heating and the microwave heating by providing a time-efficient process for uniformly stabilizing a compressed tampon pledget by forcing a gas through the compressed tampon pledget. Furthermore, the process of the present invention has the benefit of more consistent stabilization while at the same time being less dependent on incoming moisture.